#main {
    display: flex;
    justify-content: center;
    align-items: center;
    width: 100vw;
    height: 100vh;
    background: url(https://cdn.lzsjl.top/login-bk.jpg);
    background-color: white;
    background-size: cover;
    /*background: #c2ccd0;*/
}


form {
    display: flex;
    flex-direction: column;
    justify-content: flex-start;
    align-items: flex-start;
    margin: 0 0 8rem 0;
    box-sizing: border-box;
    padding: 2rem;
    background: rgba(255, 255, 255, 0.7);
    border-radius: 2rem;
}

.form-title {
    margin: 0 0 0.6rem 0;
    color: #2d2d2d;
    font-size: 2.2rem;
}
.form-item {
    margin: 1rem 0 0 0;
    width: 100%;
}

button {
    float: right;
}

@media screen and (max-width: 740px) {
    form {
        width: calc(100% - 4rem);
    }
}